In most major industrialized countries, alcohol abuse has become a major problem. On the road, in business, and at large social functions, such as sporting events. To help reduce this problem, many countries have established levels of blood alcohol above which an individual is considered legally intoxicated.
While the exact level of alcohol in the blood is only possible from an actual blood sample, it has been determined that a sufficient correlation exists between the blood alcohol level and the exhaled alcohol in an individual's breath to allow a measurement of the latter to be legal evidence of the former. The breath alcohol concentration is often expressed as an equivalent percentage of the blood alcohol concentration and is denoted by percent BAC. To measure percent BAC, a number of systems have been developed such as those utilizing a wheatstone bridge with catalytic resistance leg as shown in U.S. Pat. No. 3,764,270 granted to Collier, et al on Oct. 9, 1973, and those using a fuel cell sensor as shown in U.S. Pat. No. 3,940,251 granted to Jones, et al on Feb. 24, 1976.
While these systems are able to accurately determine percent BAC, they all require the cooperation of the individual and/or are such complex devices to operate that the individual being tested will attempt to thwart the device. For example, the patented devices supra. require the driver to exhale a deep breath into a tube which transfers the breath sample to the alcohol measuring sensor. There is no way of being able to test a driver's breath without cooperation, participation, or knowledge with these systems.
Ideally, a tester should be able to rapidly screen individuals with a device which is easily operated and unobtrusive. For example, police officers should be able to screen stopped drivers or drivers at roadblocks even where breath mints or other breath odor reducers are being used. Further, unconscious individuals should easily be tested after a traffic accident or in an emergency room environment. Similarly, it would be desirable to screen employees in hazardous occupations as they report to work or to prevent access by intoxicated individuals to bars. The system should allow for easy, single-handed operation which is totally automatic. In most situations, the accuracy of such an ideal device need not be high since it would be used primarily for screening to be followed by a more accurate measurement for legal purposes after the initial screening.
Further, it would be ideal if the testing device appeared to have some other function than the alcohol testing one. This would help allay suspicions and would help prevent antagonizing those who are intoxicated.